This invention relates to an apparatus for the detection and ranging of lightning discharges. The device may be sufficiently small to be carried in the hand and in the pockets of normal garments of apparel.
Previous developments in the field of lightning detection include ranging systems in which the distance to lightning is determined (U.S. Pat. No. 3,715,660 to Ruhnke). More elaborate devices display both azimuth and distance to the lightning activity (U.S. Pat. No. 4,023,408 to Ryan et al; U.S. Pat. No. 4,422,037 to Coleman). These inventions typically employ cross-loop antennas to detect the magnetic field component of the radiation which emanates from lightning activity and nondirectional radio antennas to detect the electric component. Comparisons of the magnetic and electric field strengths then yield approximate distances to lightning strikes.
Some devices include components which perform waveform analysis in order to distinguish lightning activity from other natural or man made electromagnetic radiation (U.S. Pat. No. 4,115,732 and U.S. Pat. No. 4,198,599 to Krider et al).
Other systems employ principals of interferometry to locate lightning activity (U.S. Pat. No. 4,841,304 to Richard et al.) or the phenomena of induced corona discharge to detect the potential of lightning strikes (U.S. Pat. No. 4,823,228 to Bittner ).
Most such devices are conceived as fixed, land based installations or airborne instruments involving substantial size, weight and expense.